Various modeling techniques have applied by researchers to predict values of surface roughness parameters in different metal cutting processes. Some examples of these methods are briefly introduced. After this an analytical model and investigation method are presented which were used to make predictions of the expected values of surface roughness parameters. Cutting experiments were performed to obtain real roughness data and to validate the proposed and realised model by face milling of 42CrMo4 specimens with two different insert shapes. Conditions and results of these experimental investigations are presented in the subsequent part of the paper, and finally the determined approximation relations are introduced that can be used to calculate the expected roughness values from theoretical data.